737 Hydraulics

Question 1

How many hydraulic systems are there?

Answer 1

3

Question 2

What are the hydraulic systems called?

Answer 2

A, B, Standby

Question 3

What is the normal hydraulic pressure range?

Answer 3

3000 psi +/- 200 psi, max 3500

Question 4

What is the purpose of the PTU? When would it operate?

Answer 4

Provide Hydraulic System B pressure sufficient to provide normal rates of operation for the Autoslats and Leading Edge Devices (LED) in the event the Hydraulic System B Engine-Driven Pump output pressure drops

Failure of Sys B

Question 5

Are there flight deck indications of PTU operation?

Answer 5

NO

Question 6

What are components specific to the Hydraulic System A?

Answer 6

Ailerons, Rudder, Elevator and Elevator Feel, Flight Spoilers (Two on Each Wing), Ground Spoilers, Alternate Brakes, No. 1 Thrust Reverser, Autopilot A, Normal NWS, Landing Gear, Power Transfer Unit (PTU) A for lAnding gear

Question 7

What are components specific to the Hydraulic System B?

Answer 7

Ailerons, Rudder, Elevator and Elevator Feel, Flight Spoilers (Two on Each Wing), Leading Edge Flaps and Slats, Normal Brakes, No. 2 Thrust Reverser, Autopilot B, Alternate NWS, Landing Gear Transfer Unit (LGTU), Autoslats, Yaw Damper, Trailing Edge Flaps) B for Brakes and flaps and yaw damper

Question 8

What does positioning a FLT CONTROL switch to STBY RUD do? looking for the logic

Answer 8

Activates the Standby Hydraulic Pump

Deactivates FLT CONTROL low pressure light Arms STBY hydraulic low pressure light

Question 9

What is the light logic when this occurs?

Answer 9

Illuminates STBY RUD ON, FLT CONT annunciator, and MASTER CAUTION lights

Question 10

What would cause the automatic operation of the Standby Hydraulic System?

Answer 10

Loss of A and/or B with flaps extended with wheel speed greater than 60 kts Loss of A and/or B with flaps extended airborne OR: The Force Flight Monitor (FFM) trips STBY SYSTEM -rudder -thrust reversers UNLESS you arm the Alternate Flaps and put the LE devices down

Question 11

During normal operations, what could cause variations in hydraulic quantity indications?

Answer 11

High demand on the system

Question 12

What would indicate a hydraulic system requires a refill? When would you see this annunciation, and where is it located?

Answer 12

Quantity below 76%, will show 30 seconds of flaps retracted on the ground.

Question 13

What pressurizes the Hydraulic System A & B reservoirs?

Answer 13

Regulated bleed air

Question 14

Which hydraulic reservoirs have a standpipe?

Answer 14

A and B

Question 15

What quantity percentage do the associated standpipe(s) protect the reservoir(s) down to?

Answer 15

A - 20% enough to protect electric pump

B - 0% but enough for PTU ops only

Question 16

With zero indicated on the Hydraulic System B quantity indicator, can the PTU still operate?

Answer 16

Yes

Question 17

When is the Standby HYD LOW QUANTITY (amber) light armed?When would it illuminate?

Answer 17

When the standby reservoir is below 50%

Question 18

What does a LOW PRESSURE (amber) light indicate? OVERHEAT (amber) light?

Answer 18

LOW PRESSURE = indicate the respective pump output pressure is low.
OVERHEAT = an overheat condition is detected in the respective system.

Question 19

Does the Hydraulic System A reservoir standpipe protect against a leak in both the engine driven pump and electric motor-driven pump? System B?

Answer 19

System A: If a leak develops in the Engine Driven Pump, the Electric Driven Pump is still available by the Standpipe, providing 20%.
If a leak develops in the Electric Driven Pump, you lose both pumps and hydraulic drops to 0%.
System B: No. Loss of both Engine and Electric Driven Pumps from a leak anywhere in the system.

Question 20

What indications, if any, would you see in the event of a Standby Hydraulic system leak?Does it affect any other system?

Answer 20

System B would decrease to 70%, affects system B

Question 21

Should both ELEC hydraulic pump switches be turned on simultaneously?
Precautions?

Answer 21

No, too much of an electrical load. #1 then #2

Need 1675 fuel in each tank for cooling

Question 22

*T/F? In System B: Extension of the Leading Edge Devices may result in up to 20% drop in hydraulic fluid quantity

Answer 22

TRUE